Disproportionate relationship between APOBEC-1 expression and apolipoprotein B mRNA editing activity.

Journal Article (Journal Article)

Apolipoprotein B (apoB) mRNA editing is a site-specific (nucleotide 6666) cytidine to uridine transition catalyzed by a cytidine deaminase, APOBEC-1, in the context of a multiprotein complex referred to as the C/U editosome. This report quantifies for the first time the effect of altering APOBEC-1 protein abundance on the proportion of edited apoB mRNAs using transfected McArdle rat hepatoma cells which had been sorted by flow cytometry into populations expressing different levels of green fluorescent protein-APOBEC-1 chimera, GFP-APOBEC. A correlation was observed in which increased expression of GFP-APOBEC protein resulted in a higher proportion of edited apoB mRNA. The number of enzyme molecules required to increase the proportion of edited apoB RNAs was disproportionately high relative to that which might have been predicted from a typical catalytic relationship. Moreover, editing of apoB mRNA at inappropriate sites (promiscuous editing) occurred in response to overexpressing GFP-APOBEC. The data suggest that experimental manipulation of APOBEC-1 abundance in the absence of other regulatory considerations will always result in some level of promiscuous editing. Coordinate expression of APOBEC-1 and the auxiliary proteins and/or regulation of their interactions may be required to increase editing activity without losing editing-site fidelity.

Full Text

Duke Authors

Cited Authors

  • Siddiqui, JF; Van Mater, D; Sowden, MP; Smith, HC

Published Date

  • October 10, 1999

Published In

Volume / Issue

  • 252 / 1

Start / End Page

  • 154 - 164

PubMed ID

  • 10502408

International Standard Serial Number (ISSN)

  • 0014-4827

Digital Object Identifier (DOI)

  • 10.1006/excr.1999.4598


  • eng

Conference Location

  • United States